1. Field of the Invention
The present invention relates generally to the golf clubs and more specifically to a golf club face or ball striking surface having dimples or depressions of selected cross-section for increasing the friction or spin characteristics between the face of the club and the ball.
2. Prior Art
It is common knowledge that golf clubs used for striking a golf ball from the teeing area to the green have a series of grooves, score lines or punch marks to help align the club head at the address to the ball and to provide optimum friction to take place at impact when the club head comes into contact with the ball. Such grooves, score lines or punch marks must meet specifications in rules set forth by the applicable golf association such as the United States Golf Association. Until relatively recently the United States Golf Association had rules severely limiting the use of grooves, score lines or punch marks on the striking surface of golf clubs. More specifically, such rules held that grooves, score lines or punch marks could only be used as decorative marking. However, in 1985 the United States Golf Association changed the rules allowing grooves in the ball striking face of golf club heads with shapes that clearly serve more than just a decorative purpose. More specifically, the 1985 rules change permitted the use of grooves having sufficient depth and shape to have some effect on the ball. Thus, it is possible as a result of the aforementioned rule change for a manufacturer of golf clubs to develop a groove or score line that can improve the friction characteristics that can occur at impact between the club head and the golf ball. For example, the ball hitting surface can now include sufficient score lines of such shape to permit the imparting of spin on the ball to produce an intentional curve in flight such as a hook or slice or to generate a higher or lower trajectory than might otherwise occur based solely upon the shape of the club head.
Unfortunately, prior art golf clubs using grooves or score lines tend to be directional in that the frictional effects on the golf ball tend to be dependent upon the angle of impact between the golf club face and the ball relative to the direction of the stroke. Consequently, if the golf club head is not perfectly square at impact, each time the ball is struck there is a lack of consistency which tends to diminish the degree of control that the golfer exerts over the trajectory of the ball thereby reducing the golfer's performance and enjoyment of the game. In addition, such prior art grooves or score lines are very susceptible to being affected by the playing conditions. For example, if the ball is around rough or wet grass or any other form of foreign material has adhered to the ball or golf club face, the degree of friction between the golf club face and the ball in the conventional grooved or score lined configuration is significantly affected. Although punch marks, unlike score lines, are not necessarily affected to any degree by the orientation of the club head, conventional decorative dimple marks tend to be too shallow to have any significant impact on the frictional characteristics between the golf club head and the ball.
There has therefore been a long-felt need for an improved golf club having a ball striking surface or face which can deliver sufficient friction to impart a desired degree of spin or other control characteristics to the ball under a wider range of playing conditions and with a substantial degree of consistency irrespective of the orientation of the golf club head relative to the ball.